Radford STA100 preset

Verified · 88/100 confidence. Complete schematic. All component values readable. Parameters derived directly from the circuit.

The Radford STA100 is a British stereo valve power amplifier built for hi-fi and professional use, with no preamp or tone controls. Each identical side has an ECC88 input stage, with an optional 600-ohm balanced XLR input transformer on the STA100B, then two EF184 pentodes as a long-tailed phase splitter and driver, and a push-pull pair of KT88s with individual bias adjustment. Outputs are 8 or 16 ohms or a 100 V line, and a silicon-diode supply feeds both sides.

• Made in: UK
• Wattage: 100W
• Channels: 1
• Preamp tubes: 2× ECC88, 4× EF184
• Power tubes: 4× KT88

Tags: british, vintage, power-amp, clean.

Schematic-derived preset files for 16 Fractal and Line 6 modelers: Axe-Fx II/XL/XL+, Axe-Fx III, FM3, FM9, and the full Helix family (Floor, LT, Rack, HX Stomp, HX Stomp XL, Native).

Gridleak extracts amp parameters from original circuit schematics using AI vision — component values, gain staging, tone stack topology, tube types — then generates native preset files for every supported modeler. Every extraction is scored 0–100 and the score is published.